Efficacy of stereotactic body radiotherapy in oligorecurrent and in oligoprogressive prostate cancer: new evidence from a multicentric study

Prostate-specific Membrane Antigen Positron Emission Tomography-detected Oligorecurrent Prostate Cancer Treated with Metastases-directed Radiotherapy: Role of Addition and Duration of Androgen Deprivation

BACKGROUND

Approximately 40-70% of biochemically recurrent prostate cancer (PCa) is oligorecurrent after prostate-specific membrane antigen (PSMA) positron emission tomography (PET) staging. Metastasis-directed radiotherapy (MDT) of PSMA-positive oligorecurrence is now frequently used, but the role of concurrent androgen deprivation therapy (ADT) remains unclear.

OBJECTIVE

To determine the effect of concurrent ADT with PSMA PET-directed MDT on biochemical progression-free survival (bRFS).

DESIGN, SETTING, AND PARTICIPANTS

This was a retrospective multicenter study of 305 patients with biochemical recurrence and PSMA PET-positive oligorecurrence following initial curative treatment between April 2013 and January 2018.

INTERVENTION

MDT with fractionated or stereotactic body radiotherapy for all PSMA-positive metastatic sites; 37.8% received concurrent ADT.

OUTCOME MEASUREMENTS AND STATISTICAL ANALYSIS

The primary outcome was bRFS, which was measured using Kaplan-Meier curves and log-rank testing. Secondary outcomes were ADT-free survival, overall survival (OS), and toxicity was analyzed using the Common Terminology Criteria for Adverse Events v4.03. Univariate and multivariate analyses were performed to determine independent clinicopathological factors.

RESULTS AND LIMITATIONS

The median follow-up was 16 mo (interquartile range 9-27). Some 96% of the patients initially had high-risk PCa. A median of one (range 0-19) nodal metastases and one (range 0-5) distant metastases were treated. MDT+ADT significantly improved bRFS and remained an independent factor (hazard ratio 0.28, 95% confidence interval 0.16-0.51; p<0.0001). bRFS was not significantly different between MDT+≤6 mo of ADT and MDT alone (p=0.121). Patients receiving MDT had 1- and 2-yr ADT-free survival of 93% and 83%, respectively. New therapies, most frequently MDT (23%), were required more frequently after MDT (85% vs 29%; p<0.001). Grade ≥3 acute toxicity was observed in 0.9% of patients and late toxicity in 2.3%.

CONCLUSIONS

In this cohort of patients with oligorecurrent PCa, concurrent ADT with MDT improved bRFS significantly, but a large number of patients treated with MDT were spared from ADT for 2yr, although a greater need for other salvage therapies was observed.

PATIENT SUMMARY

The role of concurrent androgen deprivation therapy (ADT) with radiotherapy for prostate cancer oligorecurrence identified on prostate-specific membrane antigen positron emission tomography was studied. We concluded that radiotherapy alone could prolong the time to start of ADT. However, the risk of disease progression and consequently the need for further treatments is higher after local radiotherapy alone without immediate ADT.

Local ablative therapy of oligoprogressive TKI-treated thyroid cancer

Metastatic cancer patients generally respond well to treatment with tyrosine kinase inhibitors (TKIs). However, TKI resistance occurs in almost all cases and often leads to a change in treatment. Recent guidelines, including thyroid cancer, raised the possibility of locally treating TKI-resistant oligoprogressive disease, i.e., one or a few progressing lesions in an otherwise treatment-responsive metastatic cancer, thereby obviating the need to change the ongoing TKI. To determine the benefits of this intervention, we reviewed studies on the use of LAT for TKI-treated oligoprogressive cancers. We found that in non-small cell lung cancer at least, LAT prolongs disease control and the duration of exposure to a TKI irrespective of the LAT used. Moreover, we reviewed the local ablative therapies (LATs) that are feasible for the local control of oligoprogressive thyroid cancer. Lastly, we report two illustrative cases of patients with oligoprogressive thyroid cancer treated with two different LATs while on therapy with TKIs. Both LATs extended the duration of disease control and the time of exposure to the ongoing TKI, thereby indicating that LAT is a favorable option for TKI-treated oligoprogressive thyroid cancer. Prospective randomized studies are needed to verify the benefit of LATs in terms of progression-free and overall survival in this increasingly frequent clinical setting.

Stereotactic body radiotherapy for bone oligometastatic disease in prostate cancer

Purpose

There are sparse data describing outcomes of bone-only oligometastatic prostate cancer in comparison with lymph node disease treated with stereotactic body radiotherapy (SBRT). The primary aim of this study was to report progression-free survival (PFS) data for patients with bone-only disease. Influence of hormone sensitivity and androgen deprivation therapy use was also assessed.

Methods

This is a single-centre retrospective cohort study. Hormone-sensitive and castrate-resistant patients with oligometastatic (≤ 3) bone-only prostate cancer treated with SBRT were included. Data were collected using electronic records. Kaplan–Meier survivor function, log rank test, as well as Cox regression were used to calculate PFS and overall survival.

Results

In total, 51 patients with 64 bone metastases treated with SBRT were included. Nine patients were castrate resistant and 42 patient’s hormone sensitive at the time of SBRT. Median follow-up was 23 months. Median PFS was 24 months in hormone-sensitive patients and 3 months in castrate-resistant patients. No patients experienced grade 3 or 4 toxicities. There were three in-field recurrences.

Conclusions

In this study, patients with bone oligometastatic disease showed potential benefit from SBRT with a median PFS of 11 months. Hormone-sensitive patients showed the greatest benefit, with results similar to that published for oligometastatic pelvic nodal disease treated with SBRT. Prospective randomised control trials are needed to determine the survival benefit of SBRT in oligometastatic bone-only prostate cancer and to determine prognostic indicators.

Electronic supplementary material

The online version of this article (10.1007/s00345-019-02873-w) contains supplementary material, which is available to authorized users.

Local ablative stereotactic body radiotherapy for oligometastatic prostate cancer

PURPOSE OF REVIEW

The oligometastases is considered an intermediate state of the disease between localized and wide spread metastases. Local ablative therapy to oligometastatic prostate cancer is gaining significant traction and stereotactic body radiotherapy (SBRT) is an emerging treatment modality for this patient population. In this review, we report our literature review of SBRT to prostate oligometastases. Current evidence on the role of SBRT in oligometastatic prostate cancer reported in the last 10 years was summarized. Criteria for inclusion included studies with prostate cancer only as the primary site.

RECENT FINDINGS

The unique properties of the oligometastatic prostate cancer appear to carry a better prognosis than wide spread metastatic disease, especially if these metastases are amenable to local ablative therapies. Our literature review revealed that local ablative therapy, using SBRT to prostate oligometastases, is associated with significant 2-years local control and acceptable toxicity profile.

SUMMARY

SBRT to oligometastatic prostate cancer patients is feasible and carries an acceptable toxicity profile. The randomized phase II and III trials, currently underway, should clearly define the real benefit of this approach on progression-free and overall survival outcomes.

The Dandelion Dilemma Revisited for Oligoprogression: Treat the Whole Lawn or Weed Selectively?

Oligoprogressive disease is a relatively new clinical concept describing progression at only a few sites of metastasis in patients with otherwise controlled widespread disease. In the era of well-tolerated targeted treatments, resistance inevitably occurs and overcoming this is a challenge. Local ablative therapy for oligoprogressive disease may allow the continuation of systemic treatments by overcoming the few sub-clones that have developed resistance. Stereotactic body radiotherapy is now frequently used in treating oligometastatic disease using ablative doses with minimally invasive techniques and acceptable toxicity. We discuss the current retrospective clinical evidence base supporting the use of local ablative therapy for oligoprogression in metastatic patients on targeted treatments within multiple tumour sites. As there is currently a lack of published prospective data available, the best management for these patients remains unclear. We discuss current trials in recruitment and the potential advancements in treating this group of patients with stereotactic radiotherapy.

The role of radiotherapy in metastatic prostate cancer

The current standard of care for patients with metastatic prostate cancer includes ADT with a palliative intent. Recent studies have investigated the role of local therapy in metastatic prostate cancer. While retrospective data has shown some benefit with regard to survival and delay in initiation of ADT, there has been limited prospective Randomized data. To date, there has only been one recent randomized trial revealing a survival benefit with local radiotherapy, largely benefiting patients with the lowest burden of disease. The purpose of this review is to summarize the evidence and ongoing clinical trials regarding the role of radiotherapy in metastatic prostate cancer patients.

Combining abiraterone and radiotherapy in metastatic castration-resistant prostate cancer: a review of current evidence

Prostate cancer is the second most frequent cancer worldwide, with a very high rate of progression despite treatment. The most aggressive form of the disease is known as castration-resistant prostate cancer, which carries a poor prognosis. We reviewed available literature regarding the combination of abiraterone acetate antihormonal drug and ablative radiation therapy for the treatment of metastatic castration-resistant prostate cancer. This dual treatment may enhance the effects of second-line hormonal therapy, as radiotherapy renders cancer cells more prone to immune-mediated cytotoxicity. Moreover, radiotherapy exerts its effect both on directly irradiated cells and on other distant tissues, with an abscopal effect, already demonstrated in other solid tumors. This combination treatment is safe and effective, with few adverse events. Moreover, it is of paramount importance in patients with oligoprogression of the primary disease, when current guidelines recommend continuing abiraterone treatment. Ablative radiation therapy is a noninvasive, nontoxic treatment with very high efficacy on local tumor growth control. In the available literature, the combination of radiation therapy and abiraterone acetate has prolonged both overall survival and progression-free survival, with a positive impact also on locoregional recurrence and distant metastases.

The role of hormone therapy and chemotherapy in oligometastatic prostate cancer

Oligometastatic disease was proposed by Hellman and Weichselbaum in 1995 as an intermediate tumour state between localised lesions and widespread metastases, characterised by the limited number and size of metastases in specific organs such as lung, liver, bone or even brain. The oligometastatic state has increasingly been recognised as a unique clinical state during which local ablative treatment can be effective in several types of cancer, including prostate cancer. However, the role of systemic therapy, such as hormone therapy and chemotherapy, is not yet well known. Some promising data for local ablative therapy have emerged, but it remains unclear whether local therapy can eliminate the need for, androgen-deprivation therapy (ADT), or reduce the required duration. In addition, several randomised phase III trials have demonstrated survival benefits from the addition of docetaxel or abiraterone to ADT in patients with metastatic hormone-sensitive prostate cancer. These findings suggest that such aggressive treatments may improve clinical outcomes for patients with oligometastatic prostate cancer. However, the efficacy of these treatments may depend on the volume of metastases, with higher efficacy for high-volume disease. Therefore, further investigation including stratification by disease volume is warranted. This review will discuss the current evidence and controversies surrounding the role of systemic therapy in patients with oligometastatic prostate cancer.

Oligometastases in prostate cancer: Ablative treatment

Technological advances in radiotherapy have led to the introduction of techniques such as stereotactic body radiation therapy (SBRT), allowing the administration of ablative doses. The hypothesis that oligometastatic disease may be cured through local eradication therapies has led to the increasing use of SBRT in patients with this type of disease. At the same time, scientific advances are being made to allow the confirmation of clinically suspected oligometastatic status at molecular level. There is growing interest in identifying patients with oligometastatic prostate cancer (PCa) who may benefit from curative intent metastasis-directed therapy, including SBRT. The aim is to complement, replace or delay the introduction of hormone therapy or other systemic therapies. The present review aims to compile the evidence from the main ongoing studies and results on SBRT in relation to oligometastatic PCa; examine aspects where gaps in knowledge or a lack of consensus persist (e.g., optimum schemes, response assessment, identification and diagnosis of oligometastatic patients); and document the lack of first-level evidence supporting the use of such techniques.

Radiotherapy for oligometastatic cancer: a survey among radiation oncologists of Lombardy (AIRO-Lombardy), Italy

AIMS

To evaluate the use of radiotherapy (RT) for oligometastatic cancer (OMC) among radiation oncologists in Lombardy, Italy.

METHODS AND STUDY DESIGN

A survey with 12 items regarding data of 2016 was sent to all 34 Lombardy RT centers. The survey included six general items and six specific items regarding patient/disease/treatment characteristics.

RESULTS

Thirteen centers answered the survey (38%). All centers responded to general items and 12 centers submitted patient/disease/treatment data. General items The majority of centers (8/13) consider OMC if metastases number is less than 5. The most commonly prescribed dose/fraction is 5-10 Gy (8/13) using schedules of 3-5 fractions (11/13). Patient data items A total of 15.681 patients were treated in 2016 with external beam RT in 12 responding centers, and 1.087 patients were treated for OMC (7%). Primary tumor included lung, prostate, breast, colorectal and other malignancies in 33%, 21%, 12%, 9% and 25% of all OMC patients, respectively. Brain, lymph node, lung, bone, liver and others were the most common treated sites (24%, 24%, 22%, 17%, 8% and 5%, respectively). One and more than one metastasis were treated in 75 and 25% of patients, respectively. The vast majority of patients (95%) were treated with image-guided intensity-modulated RT or stereotactic RT.

CONCLUSIONS

Seven percent of all RT patients in Lombardy are treated for OMC. Extreme hypofractionation and high-precision RT are commonly employed. The initiative of multicenter and multidisciplinary collaboration has been undertaken in order to prepare the platform for prospective and/or observational studies in OMC.

Oligometastatic prostate cancer: Reality or figment of imagination?

The term “oligometastatic prostate cancer” refers to a heterogeneous group of disease states currently defined solely on the basis of clinical features. Oligorecurrent disease, de novo oligometastases, and oligoprogressive disease likely have unique biologic underpinnings and natural histories. Evidence suggesting the existence of a subset of patients who harbor prostate cancer with limited metastatic potential currently includes disparate and overwhelmingly retrospective reports. Nevertheless, emerging prospective data have corroborated the “better‐than‐expected,” retrospectively observed outcomes, particularly in the setting of oligorecurrent prostate cancer. Improved functional imaging with prostate‐specific membrane antigen‐targeted strategies may enhance the identification of patients with oligometastatic prostate cancer in the short term. In the long term, refinement of the oligometastatic case definition likely will require biologic risk‐stratification schemes. To determine optimal treatment strategies and identify patients most likely to benefit from metastasis‐directed therapy, future efforts should focus on conducting high‐quality, prospective trials with much‐needed molecular correlative studies.

The term “oligometastatic prostate cancer” currently refers to a heterogeneous group of clinically defined disease states. To improve patient risk stratification and determine optimal treatment strategies, future efforts should focus on conducting prospective trials and determining a biologic categorization of patients with limited metastatic potential.

Combination of novel systemic agents and radiotherapy for solid tumors - part I: An AIRO (Italian association of radiotherapy and clinical oncology) overview focused on treatment efficacy

Over the past century, technologic advances have promoted the evolution of radiation therapy into a precise treatment modality allowing for the maximal administration of dose to tumors while sparing normal tissues. In parallel with this technological maturation, the rapid expansion in understanding the basic biology and heterogeneity of cancer has led to the development of several compounds that target specific pathways. Many of them are in advanced steps of clinical development for combination treatments with radiotherapy, and can be incorporated into radiation oncology practice for a personalized approach to maximize the therapeutic gain. This review describes the rationale for combining novel agents with radiation, and provides an overview of the current landscape focused on treatment efficacy.

Current and potential future role of PSMA-PET in patients with castration-resistant prostate cancer

PURPOSE

To review the current literature and discuss potential future roles of the novel positron emission tomography (PET) tracers targeting the prostate-specific membrane antigen (PSMA) in patients with castration-resistant prostate cancer (CRPC).

METHODS

A literature search on February 19th 2018 was conducted using the Medline database and www.clinicaltrials.gov . Additionally, illustrative cases of CRPC patients from our own institution who were restaged and treated based on PSMA-PET scan results are provided.

RESULTS

11 Studies met the inclusion criteria. PSMA-PET detected more metastatic lesions compared to conventional bone scan. Several patients were up-staged from non-metastatic CRPC (nmCRPC) to metastatic CRPC (mCRPC). Currently, no clear consensus exists regarding treatment response assessment in PSMA-PET scans for mCRPC patients undergoing treatment. Also, the role of PSMA-PET as a gatekeeper for systemic therapy or radioligands is currently undefined. PSMA-guided metastasis-directed radiotherapy may not only alleviate local symptoms but has the potential to defer systemic treatment in patients with oligoprogressive CRPC.

CONCLUSION

Compared to bone scan, PSMA-PET is more sensitive and specific to detect metastases but the therapeutic consequences of PSMA-PET results in the setting of CRPC remain unclear. Until future studies define the role of PSMA-PET in patients with CRPC, the current standard for imaging remains bone scan and computerized tomography.

Stereotactic body radiation therapy for liver oligometastases: predictive factors of local response by 18F-FDG-PET/CT

OBJECTIVE

To investigate metabolic parameters as predictive of local response after stereotactic body radiation therapy (SBRT) for liver-oligometastases.

METHODS

Inclusion criteria of the present retrospective study were: (a) liver oligometastases with controlled primary tumor; (b) absence of progressive disease ≥6 months; (c) metastases ≤ 3; (d) evaluation of SBRT-response by means of 18-fludeoxyglucose-PET/CT for at least two subsequent evaluations; (e) Karnofsky performance status >80; (f) life-expectancy >6 months. The following metabolic parameters were defined semi-quantitatively for each metastases: (1) standardized uptake value (SUVmax; (2) SUV-mean; (3) metabolic tumor volume (MTV), tumor volume with a SUV ≥3, threshold 40%; (4) total lesion glycolysis (TLG), i.e. the product of SUV-mean and MTV. Local control was defined as absence of recurrence in the field of irradiation.

RESULTS

41 liver metastases were analyzed. Pre-SBRT, median SUV-max was 8.7 (range, 4.5-23.59), median SUV-mean was 4.6 (range, 3-7.5), median MTV was 5.7 cc (range, 0.9-80.6) and median total lesion glycolysis was 24.1 (range, 3.6-601.5). At statistical analysis, metastases with SUV-mean >5 (p 0.04; odds ratio 4.75, sensitivity = 50%, specificity = 82.6%, area under the curve 0.66) and SUV-max >12 (p 0.02; odds ratio 5.03, sensitivity = 69%, specificity = 70%, area under the curve = 0.69) showed higher rates of infield-failure compared to the remaining lesions.

CONCLUSION

According to current findings, pre-SBRT SUV-max and SUV-mean could be predictable of local response in liver oligometastases. Advances in knowledge: Present findings could support the hypothesis that fludeoxyglucose-PET/CT may be a powerful tool to predict tumor control. Specifically, current results might be helpful for clinicians in the decision-making process regarding liver oligometastatic patient selection as well as the individual therapy stratification distinguishing between slowly local progressing patients and rapidly progressing patients.

Stereotactic Body Radiation Therapy for Oligometastatic Ovarian Cancer: A Step Toward a Drug Holiday

PURPOSE

To evaluate stereotactic body radiation therapy (SBRT) for metachronous oligometastatic ovarian cancer patients in terms of local control, delay of systemic treatment, survival outcomes, and toxicity.

METHODS AND MATERIALS

Retrospective data collection from a single institution was performed. The inclusion criteria were as follows: (1) oligorecurrent or oligoprogressive disease in ovarian cancer patients during or after systemic therapy; (2) surgery or other local therapies not feasible; and (3) relative contraindication to systemic therapy for reasons such as unavailability of additional chemotherapy lines or refusal of the patient. Tumor response and toxicity were evaluated using the Response Evaluation Criteria in Solid Tumors and the Common Terminology Criteria for Adverse Events version 4.03, respectively. A new systemic therapy regimen was started after an SBRT treatment course in 57 of 109 cases (52.3%). Local progression-free survival, progression-free survival, and overall survival were calculated via the Kaplan-Meier method. The systemic treatment-free interval was calculated in cases without concomitant systemic therapy.

RESULTS

Between May 2012 and December 2016, 82 patients (156 lesions) underwent SBRT with a median dose of 24 Gy in 3 fractions. The median follow-up period was 17.4 months. Patients received a median of 3 systemic therapy regimens prior to SBRT. Concomitant systemic therapy was performed for 29 lesions (18.6%). Among 152 evaluable lesions, a complete radiologic response, partial response, stabilization, and progressive disease were observed in 91 (60%), 26 (17%), 24 (16%), and 11 (7%), respectively. No grade 3 or 4 acute or late toxicities were observed. The median systemic treatment-free interval after SBRT was 7.4 months, and 1 of 3 patients was disease free at 1 year after SBRT. The actuarial 2-year local progression-free survival, progression-free survival, and overall survival rates were 68%, 18%, and 71%, respectively. The pattern of failure was predominantly out of field.

CONCLUSIONS

SBRT for oligometastatic ovarian cancer showed good local control and a good toxicity profile. It might be an appealing alternative to other invasive local therapies to delay systemic therapy in the case of chemorefractory disease or intolerance to systemic agents.

Salvage Low Dose Rate Brachytherapy For Recurrent Prostate Cancer After External Beam Radiotherapy: Results From A Single Institution With Focus On Toxicity And Functional Outcomes

Background/aim:

Low dose rate brachytherapy has been used as salvage therapy for locally recurrent prostate cancer (PC) after primary external beam radiation therapy (EBRT), along with surgery and cryotherapy. All these techniques, in particular, when applied to the whole gland, involve a relatively high risk of toxicity and may worsen the patient’s quality of life. Our aim is to evaluate the results of whole-gland salvage brachytherapy (SBT) after primary EBRT in terms of toxicity, functional outcomes, and efficacy.

Materials and methods:

We retrospectively reviewed clinical data on 19 patients consecutively treated with SBT at our institution between June 2012 and November 2015. Local recurrences were identified with 11C-choline positron emission tomography/computed tomography and pelvic magnetic resonance imaging after biochemical recurrence according to Phoenix criteria (prostate-specific antigen nadir + 2). Low dose rate brachytherapy was performed by ¹²⁵I permanent seeds implantation to the whole prostate gland, with a prescription dose of 130 Gy. At the time of SBT, only 2 patients were receiving androgen deprivation therapy. Acute and late toxicities were recorded using the CTCAE 4.0 scoring system. Quality of life was assessed using IPSS (International Prostate Symptoms Score) and IIEF (International Index of Erectile Function) questionnaires at baseline and 6, 12, and 24 months after SBT, and the respective mean values were compared using Student t test. Biochemical relapse-free survival (BRFS) was also calculated.

Results:

Median follow-up after SBT was 24 months. Of 19 patients, 2 patients experienced a G3 cystitis (10.2%) and 1 patient experienced a G4 proctitis (5.3%), respectively. Mean pre-SBT IPSS scores and 6, 12, and 24 months after SBT were 5.84, 10.22, 15.72, and 8.10, respectively. Mean pre-SBT IIEF scores and 6, 12, and 24 months after SBT were 8.42, 3.55, 7.89, and 6.40, respectively. At the time of analysis, only 2 patients showed a biochemical relapse (3-year BRFS 85.2%). The Student t test demonstrated a worsening of functional outcome 6 months and 1 year after treatment but a subsequent improvement 2 years after SBT.

Conclusions:

Salvage brachytherapy for recurrent PC after primary EBRT seems to be a feasible treatment for selected patients. Our series revealed a severe toxicity peak 6 months and 1 year after local re-treatment and then they decrease. Early BRFS rates are good. However, these are very preliminary results so further patient accrual, long-term follow-up, and prospective trials are needed in the future.